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specify JPAQL EXTRACT function #314

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Dec 2, 2021
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specify JPAQL EXTRACT function #314

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78 changes: 69 additions & 9 deletions spec/src/main/asciidoc/ch04-query-language.adoc
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Original file line number Diff line number Diff line change
Expand Up @@ -320,9 +320,9 @@ CHAR_LENGTH, CHARACTER_LENGTH, POSITION, and UNKNOWN are not currently
used: they are reserved for future use.],
BOTH, BY, CASE, CHAR_LENGTH, CHARACTER_LENGTH, CLASS, COALESCE, CONCAT,
COUNT, CURRENT_DATE, CURRENT_TIME, CURRENT_TIMESTAMP, DELETE, DESC,
DISTINCT, ELSE, EMPTY, END, ENTRY, ESCAPE, EXISTS, FALSE, FETCH, FROM,
FUNCTION, GROUP, HAVING, IN, INDEX, INNER, IS, JOIN, KEY, LEADING, LEFT,
LENGTH, LIKE, LOCATE, LOWER, MAX, MEMBER, MIN, MOD, NEW, NOT, NULL,
DISTINCT, ELSE, EMPTY, END, ENTRY, ESCAPE, EXISTS, EXTRACT, FALSE, FETCH,
FROM, FUNCTION, GROUP, HAVING, IN, INDEX, INNER, IS, JOIN, KEY, LEADING,
LEFT, LENGTH, LIKE, LOCATE, LOWER, MAX, MEMBER, MIN, MOD, NEW, NOT, NULL,
NULLIF, OBJECT, OF, ON, OR, ORDER, OUTER, POSITION, SELECT, SET, SIZE,
SOME, SQRT, SUBSTRING, SUM, THEN, TRAILING, TREAT, TRIM, TRUE, TYPE,
UNKNOWN, UPDATE, UPPER, VALUE, WHEN, WHERE.
Expand Down Expand Up @@ -1694,7 +1694,8 @@ functions_returning_numerics ::=
SQRT(arithmetic_expression) |
MOD(arithmetic_expression, arithmetic_expression) |
SIZE(collection_valued_path_expression) |
INDEX(identification_variable)
INDEX(identification_variable) |
extract_datetime_field
----

The ABS function takes a numeric argument and
Expand Down Expand Up @@ -1735,11 +1736,62 @@ AND INDEX(w) = 0
functions_returning_datetime :=
CURRENT_DATE |
CURRENT_TIME |
CURRENT_TIMESTAMP
CURRENT_TIMESTAMP |
extract_datetime_part
----

The datetime functions return the value of
current date, time, and timestamp on the database server.
The functions CURRENT_DATE, CURRENT_TIME, and CURRENT_TIMESTAMP
return the value of the current date, time, or timestamp on the database
server, respectively.

The EXTRACT function takes a datetime argument and one of the following
field type identifiers: YEAR, QUARTER, MONTH, WEEK, DAY, HOUR, MINUTE,
SECOND, DATE, TIME.

EXTRACT returns the value of the corresponding field or part of the
datetime.

----
extract_datetime_field :=
EXTRACT(datetime_field FROM datetime_expression)

datetime_field := identification_variable
----

For the following field type identifiers, EXTRACT returns an integer
value:

- YEAR means the calendar year.
- QUARTER means the calendar quarter, numbered from 1 to 4.
- WEEK means the ISO-8601 week number.
- DAY means the calendar day of the month, numbered from 1.
- HOUR means the hour of the day in 24-hour time, numbered from 0 to 23.
- MINUTE means the minute of the hour, numbered from 0 to 59.
- SECOND means the second of the minute, numbered from 0 to 59.
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Ugh, @lukasj I screwed up here.

Actually I think it's much better if SECOND, unlike the other fields, includes the fractional part. So it's a floating point value, not an integer. (Databases are pretty inconsistent here, but this interpretation can be implemented portably.)


It is illegal to pass a datetime argument which does not have the given
field type to EXTRACT.

----
extract_datetime_part :=
EXTRACT(datetime_part FROM datetime_expression)

datetime_part := identification_variable
----

For the following field type identifiers, EXTRACT returns a part of the
datetime value:

- DATE means the date part of a datetime.
- TIME means the time part of a datetime.

It is illegal to pass a datetime argument which does not have the given
part to EXTRACT.

[source,sql]
----
FROM Course c WHERE c.year = EXTRACT(YEAR FROM CURRENT_DATE)
----

===== Invocation of Predefined and User-defined Database Functions [[a5311]]

Expand Down Expand Up @@ -2998,11 +3050,13 @@ functions_returning_numerics ::=
SQRT(arithmetic_expression) |
MOD(arithmetic_expression, arithmetic_expression) |
SIZE(collection_valued_path_expression) |
INDEX(identification_variable)
INDEX(identification_variable) |
extract_datetime_field
functions_returning_datetime ::=
CURRENT_DATE |
CURRENT_TIME |
CURRENT_TIMESTAMP
CURRENT_TIMESTAMP |
extract_datetime_part
functions_returning_strings ::=
CONCAT(string_expression, string_expression{, string_expression}*) |
SUBSTRING(string_expression, arithmetic_expression[, arithmetic_expression]) |
Expand All @@ -3011,6 +3065,12 @@ functions_returning_strings ::=
UPPER(string_expression)
trim_specification ::= LEADING | TRAILING | BOTH
function_invocation ::= FUNCTION(function_name{, function_arg}*)
extract_datetime_field :=
EXTRACT(datetime_field FROM datetime_expression)
datetime_field := identification_variable
extract_datetime_part :=
EXTRACT(datetime_part FROM datetime_expression)
datetime_part := identification_variable
function_arg ::=
literal |
state_valued_path_expression |
Expand Down